Pregnant guinea pigs will be exposed to tape recorded textile mill (weaving room) noise. The hearing level of offspring will be measured and compared with that of offspring of otherwise identical mothers. Study of the effects of high level sounds on fetuses in utero is important because: 1. Many women are moving into very noisy occupations, some as jet engine mechanics where whole body exposures exceed 120 dBA, 2. a period of enhanced susceptibility was recently demonstrated to occur in hamsters beginning at the point of final maturation of the ear, i.e., about 20 days post partum. 3. the equivalent period on humans and guinea pigs occurs near the end of the last trimester, 4. a Polish study recently found elevated hearing thresholds in guinea pigs exposed in utero to weaving room noise.